Recently, a robot hand apparatus having a plurality of fingers mimicking a hand of a human has been known.
This kind of robot hand apparatus comprises a palm section, which corresponds to a palm of a hand, and a plurality of finger mechanisms each elongates from the palm section. In each finger mechanism, a plurality of phalange parts is pivotably joined each other through a finger joint, and serves as a link mechanism which flexes or stretches the phalange part of a palm section side (base-end side) by motor power, so that the phalange parts next to the phalange part of the palm section side are flexed or stretched one by one.
An example of the conventional robot hand apparatus will be explained below with two examples.
As first example of conventional robot hand apparatus, the robot hand apparatus disclosed in Japanese unexamined patent publication JP No. 2003-266357 has been known. In this apparatus, each finger mechanism is respectively provided with a single motor and can be flexed by the individually provided motor. Therefore, a humanlike grip motion, i.e. the motion to flex each finger one by one from a little finger (little) can be achieved.
As second example of conventional robot hand apparatus, the robot hand apparatuses disclosed in Japanese unexamined patent publication JP No. 2002-103269 and JP No. 2003-181787 have been known.
In this conventional robot hand apparatus, each finger mechanism respectively connects with a corresponding wiring at base-side end thereof, and the other end of each wiring connects with the same motor through a plurality of members. Thus, since only one motor is required for actuating each finger mechanism, this allows the improvement of the space efficiency.
However, in the robot hand apparatus of first example, the humanlike grip motion (a regular grip motion) can be achieved, but the space efficiency (saving of a space) becomes worse due to a plurality of motors installed for actuating respective finger mechanisms.
In the robot hand apparatus of second example, on the other hand, since the number of the motor to be installed is only one, the space efficiency can be improved. However, a humanlike grip motion cannot be achieved. This is because respective finger mechanisms are simultaneously flexed by the single motor.
In the robot hand apparatus of second example, furthermore, when gripping an object having a complicated shape, for example, the motor cannot pull the wiring any more if any one of five finger mechanisms comes in contact with the object. In this case, since the others of five finger mechanisms cannot come in contact with the object, the sufficient grip of the object cannot be achieved.
Therefore, the robot hand apparatus, which can improve the space efficiency and provide a humanlike grip motion, i.e. the motion flexing sequentially fingers from a little, has been mainly required.